Risk reduction of electrical hazards

ABSTRACT

An apparatus includes an enclosure, a power switch, one or more power converters and a wire. The enclosure may include a door and one or more apertures. The enclosure may be mechanically attachable to an external side of an industrial control panel with the apertures aligned to one or more openings in a wall of the industrial control panel. The power switch may be mounted inside the enclosure and configured to switch electrical power from a line-side power line to a load-side power line. The load-side power line may be configured to transfer the electrical power through at least one of the apertures. The power converters may be configured to generate a low-voltage electrical power from the electrical power. The wire may be configured to transfer the low-voltage electrical power through at least one of the apertures.

This application relates to U.S. Ser. No. 15/444,717, filed Feb. 28,2017, which relates to U.S. Provisional Application No. 62/389,755,filed Mar. 9, 2016, each of which are hereby incorporated by referencein their entirety.

FIELD OF THE INVENTION

The invention relates to industrial control power distribution generallyand, more particularly, to a method and/or apparatus for implementingrisk reduction of electrical hazards.

BACKGROUND

Per the North American workplace electrical safety standards publishedby the National Fire Protection Association and the Canadian StandardsAssociation, a conventional industrial control panel is consideredenergized until validated to be de-energized. The validation iscompleted using an adequately rated voltage detector. Depending on arisk category of the installation being serviced, personal protectionequipment of varying degrees is worn by an electrical worker to completethe validation as the validation involves the electrical worker beingwithin a prohibited approach boundary of the electrical hazard.

After a main power disconnect switch has been opened and a load sidecircuit confirmed de-energized, a top area of the main power disconnectswitch inside the industrial control panel is still energized. With adoor of the industrial control panel open, the presence of liveconductors exposes the electrical worker to potential electrocution andarc-flash hazards. In such a case, the appropriate personal protectionequipment should be worn the entire time the panel is being worked on bythe electrical worker. The personal protection equipment for typicalindustrial installations is expensive, cumbersome and time consuming todon.

It would be desirable to implement a method and/or apparatus forimplementing risk reduction of electrical hazards.

SUMMARY

The invention concerns an apparatus including an enclosure, a powerswitch, one or more power converters and a wire. The enclosure mayinclude a door and one or more apertures. The enclosure may bemechanically attachable to an external side of an industrial controlpanel with the apertures aligned to one or more openings in a wall ofthe industrial control panel. The power switch may be mounted inside theenclosure and configured to switch electrical power from a line-sidepower line to a load-side power line. The load-side power line may beconfigured to transfer the electrical power through at least one of theapertures. The power converters may be configured to generate alow-voltage electrical power from the electrical power. The wire may beconfigured to transfer the low-voltage electrical power through at leastone of the apertures.

BRIEF DESCRIPTION OF THE FIGURES

Embodiments of the invention will be apparent from the followingdetailed description and the appended claims and drawings in which:

FIG. 1 is a diagram of a system;

FIG. 2 is a block diagram of the system in accordance with an embodimentof the invention;

FIG. 3 is a block diagram of a variation of the system;

FIG. 4 is a block diagram of another variation of the system;

FIG. 5 is a block diagram of a portion of an isolated control panel;

FIG. 6 is a diagram of a mounting for a window;

FIG. 7 is a diagram of a door sticker;

FIG. 8 is a perspective diagram of a portion of an interlock devicewithin the industrial control panel;

FIG. 9 is a perspective diagram of a portion of the interlock devicewithin the isolated control panel;

FIG. 10 is a perspective diagram of a relief chamber;

FIG. 11 is a perspective diagram of the relief chamber from an enclosureside;

FIG. 12 is a block diagram of a remote monitoring configuration;

FIG. 13 is a block diagram of another variation of the system;

FIG. 14 is a diagram of a variation of the system; and

FIG. 15 is a block diagram of the system of FIG. 14 in accordance withan embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention include providing a method and/orapparatus for implementing risk reduction of electrical hazards that may(i) reduce a risk of shock and arc-flash hazards, (ii) reduce a risk ofshock and arc-blast hazards, (iii) augment existing industrial controlpanels, (iv) provide low-voltage power inside the industrial controlpanel, (v) provide interlocks of the doors and/or (vi) be implemented inone or more housings.

Embodiments of the invention generally provide an isolated control panel(or enclosure) attachable to a common industrial control panel. Theisolated control panel may allow an interior of the industrial controlpanel to be de-energized of all potentially-lethal electrical power. Thede-energization of the interior of the industrial control panelgenerally eliminates shock hazards and adds a second line and a thirdline of defense against arc-flash and/or arc-blast hazards.

The isolated control panel may allow employers to formulate realisticelectrical safety policies and procedures for qualified employeesaccessing the industrial control panel. The isolated control panel mayalso provide relevant worker safety while maximizing plant operationalefficiency and further assists the employer in making sound hazardassessments at each installation. The de-energization of the industrialcontrol panel may simplify work practices to prevent electric shockand/or other injuries resulting from either direct or indirectelectrical contacts. In many instances, the isolated control panel, aspart of a complete company electrical safety policy and procedure, mayprovide enough adequate risk reduction of a particular installation asto lower the level of personal protection equipment used by thequalified employee when entering the locked out industrial controlpanel.

Referring to FIG. 1, a diagram of a system 80 is shown. The system (orapparatus) 80 generally comprises an enclosure (or housing) 82 and anenclosure (or housing) 100. The enclosure 82 may implement a commonindustrial control panel. The enclosure 100 may implement an isolatedcontrol panel. The isolated control panel 100 may be mechanicallyattachable to an external side of the industrial control panel 82.

The industrial control panel 82 may be operational to switch and/orroute high-voltage electrical power (e.g., 575 volts AC three-phasepower) from an input source to one or more external loads. Theindustrial control panel 82 generally comprises a handle (or lever) 84mounted on a front of the industrial control panel 82. The handle 84 mayimplement a main power disconnect handle having an “on” position and an“off” position. The main power disconnect handle 84 may include atypical interlock mechanism that prevents a door of the industrialcontrol panel 82 from opening while the main power disconnect handle 84is in the “on” position. The interlock mechanism may allow the door ofthe industrial control panel 82 to be manually opened while the mainpower disconnect handle 84 is in the “off” position.

The isolated control panel 100 generally comprises an enclosure (orhousing) 101 and a door 118. The enclosure 101 generally comprisesmultiple indicators (or lights) 102, multiple test points (or stations)104, multiple indicators (or lights) 106, multiple test points (orstations) 108, an indicator (or light) 110, a lever (or switch) 112, awindow 114, an optional window 116, multiple hinges 120 a-120 b, a lever(or handle) 122 and one or more blocks (or circuits) 124.

The enclosure 101 may implement a rectangular-shaped box. The enclosure101 may be configured to house various components and provide mechanicalprotection against electrical shock hazards, arc-flash hazards and/orarc-blast hazards. The enclosure 101 may be fabricated of anelectrically conductive material (e.g., steel) and is electricallyconnected to the industrial control panel 82 for grounding purposes. Invarious embodiments, the enclosure 101 may be several feet tall (e.g.,46 inches), by approximately a foot wide (e.g., 15 inches) andapproximately a foot deep (e.g., 12 inches). Other dimensions may beimplemented to meet the design criteria of a particular application.

The indicators 102 may implement multi-phase (e.g., three-phase)line-side voltage indicators. Each line-side voltage indicator 102 maybe operational to illuminate while electrical power is present on acorresponding line-side power supply line. If electrical power is absentfrom any one or more of the line-side power supply lines, thecorresponding line-side voltage indicator 102 may be dark. In someembodiments, the line-side voltage indicators 102 may be mounted in thedoor 118.

The test points 104 may implement multi-phase (e.g., three-phase)line-side non-contact or high-impedance touch-test-point voltage teststations. Each test station 104 may be operational to provide testvoltages indicative of the voltage on a corresponding line-side powersupply line (e.g., phase-to-phase voltages and/or phase-to-groundvoltages). The test stations 104 may be configured to provide electricalisolation between the line-side power supply lines and contact points onthe exterior of the test stations 104. In some embodiments, the teststations 104 may be mounted in the door 118.

The indicators 106 may implement multi-phase (e.g., three-phase)load-side voltage indicators. Each load-side voltage indicator 106 maybe operational to illuminate while electrical power is present on acorresponding load-side power supply line. If electrical power is absentfrom any one or more of the load-side power supply lines, thecorresponding load-side voltage indicator 104 may be dark. In someembodiments, the line-side voltage indicators 106 may be mounted in thedoor 118.

The test points 108 may implement multi-phase (e.g., three-phase)load-side non-contact or high-impedance touch-test-point voltage teststations. Each test station 108 may be operational to provide testvoltages indicative of the voltage on a corresponding load-side powersupply line (e.g., phase-to-phase voltages and/or phase-to-groundvoltages). The test stations 108 may be configured to provide electricalisolation between the load-side power supply lines and contact points onthe exterior of the test stations 108. In some embodiments, the teststations 108 may be mounted in the door 118.

The light 110 may implement a control power status light forlow-voltage. The control power status light 110 may be visible from theexterior of the enclosure 101. The control power status light 110 may beilluminated while a low-voltage power is present inside the enclosure101. The control power status light 110 may be dark while thelow-voltage power is absent from inside the enclosure 101. In variousembodiments, the control power status light 110 may be mounted in thedoor 118.

The lever 112 may implement a control power disconnect lever. In someembodiments, the lever 112 may be a fused control power disconnectlever. The control power disconnect lever 112 is generally operationalto switch electrical supply power to a power converter that generatesone or more lower voltages (e.g., 120 volts AC single-phase power and/or24 volt DC power). While the control power disconnect lever 112 is in an“on” position, the electrical power may be transferred from a power lineto the power converter inside the isolated control panel 100. While thecontrol power disconnect lever 112 is in an “off” position, theelectrical power may be isolated from the power converter.

The window 114 may implement an explosion proof front viewing window.The window 114 may provide a view of the interior of the enclosure 101.In various embodiments, the front window 114 may be positioned on thedoor 118 to show a front view of a main power disconnect switch. Otherlocations of the window 114 may be implemented to meet the designcriteria of a particular application.

The window 116 may implement an explosion proof side viewing window. Theside window 116 may provide another view of the interior of theenclosure 101 from a different angle than the window 114. In variousembodiments, the side window 116 may be positioned on a side of theenclosure 101 to show a side view of the main power disconnect switch.Other locations of the window 116 may be implemented to meet the designcriteria of a particular application.

The hinges 120 a-120 b may be configured to pivotally attach the door118 to the enclosure 101. While two hinges 120 a-120 b are illustrated,other numbers of hinges may be implemented. In some embodiments, asingle piano-style hinge may be used to secure the door 118 to theenclosure 101.

The lever 122 may implement a door lever. The lever 122 is generallyoperational to hold the door 118 shut while the door 118 is closed andthe lever 122 is in a “closed” position. While the lever 122 is in an“open” position, the door 118 may be free to rotate about the hinges 120a-120 b, if safety interlocks permit.

The circuit 124 may implement one or more low-voltage (e.g., 120 voltAC) receptacles. The receptacles 124 may receive single-phase electricalpower from the power converter. While electrical power is present in thepower converter, a power line may transfer the electrical power (e.g.,120 volt AC power) through a power line to the receptacles 124. One ormore of the receptacles 124 may be mounted on a side surface (asillustrated), top surface and/or bottom surface of the enclosure 101 andmay be accessible from outside the enclosure 101. In variousembodiments, one or more receptacles 124 may be mounted in the door 118.In some embodiments, one or more receptacles 124 may be mounted insidethe enclosure 101.

Referring to FIG. 2, a block diagram of an example implementation of thesystem 80 is shown in accordance with an embodiment of the invention.The industrial control panel 82 generally includes the main powerdisconnect handle 84, a branch circuit protector 86, a low-voltage wire88 and a power line 90. The isolated control panel 100 generallyincludes the line-side voltage indicators 102, the line-side teststation 104, the load-side voltage indicators 106, the load-side teststation 108, the control power status light 110, the control powerdisconnect lever 112, the front window 114 and the side window 116. Theisolated control panel 100 may also comprise a block (or circuit) 130,block (or circuit) 132, a block (or circuit) 134, an interlock device(or mechanism) 136, one or more blocks (or circuits) 138, an interlockdevice (or mechanism) 142, a power line (or wire) 150, a power line (orwire) 152, a power line (or wire) 154, a power line (or wire) 156, apower line (or wire) 160, a power line (or wire) 162, a power line (orwire) 164, a power line (or wire) 165, a power line (or wire) 166, and acable actuator (or link) 170.

The circuit 130 may implement a line-side power distribution block. Theline-side power distribution block 130 is generally operational todistribute multiple-phase (e.g., three-phase) line-side electrical powerfrom the multi-phase power line 150 to the circuit 132. The electricalpower may be transferred from the line-side power distribution block 130to the block 132 via the multi-phase line-side power line 152. Invarious embodiments, the line-side power distribution block 130 may alsodistribute single-phase electrical power to the control power disconnectlever 112 via the power line 168. The current available on the powerlines 150, 152 and 168 may be a hazardous available fault current.

The circuit 132 may implement a main power disconnect switch. The mainpower disconnect switch 132 is generally operational to alternatelyconnect and disconnect the multi-phase electrical power received fromthe line-side power distribution block 130 to the circuit 134 via theload-side power line 154. The main power disconnect switch 132 may becontrolled by the cable actuator 170. In some embodiments, the powerlines 150 and 168 may be connected directly to the main power disconnectswitch 132 and the line-side power distribution block 130 may beeliminated. The multi-phase electrical power received by the main powerdisconnect switch 132 may also be transferred to the line-side voltageindicator 102 and the line-side test station 104 via the multi-phasepower line 160.

The circuit 134 may implement a load-side power distribution block. Theload-side power distribution block 134 is generally operational todistribute multiple-phase (e.g., three-phase) load-side electrical powerreceived from the main power disconnect switch 132 to the industrialcontrol panel 82 via the multi-phase power line 156. The electricalpower from the output side of the load-side power distribution block 134may be connected to the branch circuit protector 86, located in theindustrial control panel 82. The power line 156 may pass through one ormore apertures 140 in the walls of the isolated control panel 100 andcontinue in the industrial control panel 82 as the power line 90. Thepower line 90 is generally connected to the branch circuit protector 86.The multi-phase electrical power received by the load-side powerdistribution block 134 may also be transferred to the load-side voltageindicator 106 and the load-side test station 108 via the multi-phasepower line 162.

The interlock device 136 is generally operational to keep the door 118in the closed position while the control power disconnect lever 112 isin the “on” position. While the control power disconnect lever 112 is inthe “off” position, the interlock device 136 may allow the door 118 tobe open, if the door lever 122 and the interlock device 142 permit.

Each circuit 138 may implement a power converter circuit (one shown forclarity). Each power converter 138 is generally operational to convertsingle-phase electrical power received from the control power disconnectlever 112 into low-voltage electrical power (e.g., 24 volts DC power or120 volts AC power). The single-phase electrical power may betransferred via the power line 166. In some embodiments, a single powerconverter 138 may be implemented. In other embodiments, multiple (e.g.,2) power converters 138 may be implemented, each generating the sametype or a different type of low-voltage electrical power. For example,the power converter 138 may implement a transformer and/or rectifierthat converts 600 volt AC electrical power or 480 volt AC electricalpower to 120 volt AC electrical power and/or 24 volt DC electricalpower.

Single-phase electrical power may be received by the power converter 138from the line-side power distribution block 130 through the controlpower disconnect lever 112. While the control power disconnect lever 112is in the “on” position, electrical power may be supplied from theline-side power distribution block 130, through power line 168, throughthe control power disconnect lever 112, and through the power line 166to the power converter 138. While the control power disconnect lever 112is in the “off” position, no electrical power is provided to the powerconverter 138.

The low-voltage power may be presented by the power converter 138 on thepower lines 164 and 165 while electrical power is received on the powerline 166. The power line 164 may transfer the low-voltage power to thecontrol power status light 110. The power line 165 may transfer thelow-voltage power through one or more of the apertures 140 where theline continues inside the industrial control panel 82 as the low-voltagewire 88.

The apertures 140 may be implemented as gasketed apertures. Theapertures 140 are generally configured to provide passage between aninterior of the industrial control panel 82 and an interior of theisolated control panel 100. The apertures 140 may convey multiple powerlines/wires and the cable actuator 170.

The interlock device 142 is generally configured to prevent the door 118of the isolated control panel 100 and/or a door of the industrialcontrol panel 82 from opening when the main power disconnect handle 84is in the “on” position. The interlock device 142 may be defeatable witha standard tool. The interlock device 142 may also prevent the mainpower disconnect handle 84 from moving from the “off” position to the“on” position when the door 118 of the isolated control panel 100 and/orthe door of the industrial control panel 82 is open. The locking featureof the interlock device 142 with the main power disconnect handle 84 mayalso be defeatable with a standard tool.

The cable actuator 170 generally provides a mechanical link between themain power disconnect switch 132, located inside the isolated controlpanel 100, and the main power disconnect handle 84, located on theindustrial control panel 82. The cable actuator 170 may be connectedsuch that operating the main power disconnect handle 84 also operatesthe main power disconnect switch 132 in a synchronic manner. The cableactuator 170 may pass between the isolated control panel 100 and theindustrial control panel 82, through at least one of the apertures 140.

Referring to FIG. 3, a block diagram of another example implementationof a system 80 a is shown. The system 80 a may be a variation of thesystem 80. The system 80 a generally comprises the system 80 with anadditional enclosure (or housing) 180 and a conduit 182. The line-sidepower distribution block 130 may be mounted in the enclosure 180. Theenclosure 180 may be mounted to a top of the industrial control panel82. The multi-phase power line 150 may be received by the line-sidepower distribution block 130. The ridged conduit 182 may convey themulti-phase power line 152 from the line-side power distribution block130 to the main power disconnect switch 132. The conduit 182 may alsoconvey the power line 168 from the line-side power distribution block130 to the control power disconnect lever 112.

Referring to FIG. 4, a block diagram of another example implementationof a system 80 b is shown. The system 80 b may be a variation of thesystem 80 a with a modified industrial control panel 82 a. The powerfrom the output side of the load-side power distribution block 134 maybe connected to the branch circuit protector 86 located in theindustrial control panel 82 a, as in the system 80 a. The multi-phasepower line 156 generally passes through the one or more apertures 140 aof the isolated control panel 100 and the industrial control panel 82 a.The apertures 140 a may transfer the electrical power to the power line90 through the use of a rated disconnect plug 92 and a correspondingreceptacle 94.

Referring to FIG. 5, a block diagram of an example implementation of aportion of the isolated control panel 100 is shown. The isolate controlpanel 100 may include the control power status light 110, thereceptacles 124, the power converter 138, a block (or circuit) 220, ablock (or circuit) 224 and a block (or circuit) 226. The isolatedcontrol panel 100 may also include a power line (or wire) 200, a powerline (or wire) 202, a power line (or wire) 204 and a power line (orwire) 206.

The circuit 220 may implement a horn and/or a beacon. The horn/beaconmay be operational to trigger while the door 118 is open and electricalpower is present on the line-side power distribution block 130. Whileelectrical power is present on the line-side power distribution block130, the power line 168 may transfer the electrical power to the powerline 200 and to the horn/beacon 220. A power line 202 may provideelectrical power from the power converter 138 to the receptacles 124.The power line 164 may provide electrical power to the control powerstatus light 110.

The circuit 224 may implement a light on the interior of the enclosure101. The interior light 224 may be powered from the power converter 138via the power line 204. The interior line 224 may include an exterioron/off switch that enables the interior light 224 to be switched on whendesired, and off when not in use.

The circuit 226 may implement a programmable controller. Theprogrammable 226 may be operational to monitor various auxiliary signalsinside the enclosure 101 and report the status of the auxiliary signalsto a remote monitoring station. The programmable controller 226 may bepowered by the power converter 138 through the power line 206.

Referring to FIG. 6, a diagram of an example mounting of a window isshown. The window illustrated may be representative of the front window114 and/or the side window 116. A wall 240 of the isolated control panel100 may include an opening 242 for each window. For the front window114, the opening 242 may be formed in the door 118. For the side window116, the opening 242 may be formed in the enclosure 101. In someembodiments, the opening 242 may be generally rectangular in shape.Other shapes of openings may be implemented to meet the design criteriaof a particular application. Each window 114/116 may be mounted on aninterior side of the wall 240. Any pressure created by an arc-flashand/or arc-blast inside the isolated control panel 100 generally forcesthe windows 114 and 116 against the wall 240, thereby containing thepressure and preventing an electrical worker (or operator or person)and/or bystander from being exposed to the blast.

Respective frames 244 may be configured to hold the windows 114 and 116against the wall 240. Each frame 244 may include an opening 246 alignedwith the opening 242. The opening 246 may be generally rectangular inshape. Other shapes of openings may be implemented to meet the designcriteria of a particular application. Multiple (four) bolts 248 a-248 nmay be welded to the wall 240 proximate each window 114/116. The bolts248 a-248 n may be inserted into corresponding holes in the frame 244 toallow the frame 244 to encapsulate the window 114/116. Multiple nuts 250a-250 n may be tightened to the bolts 248 a-248 n to secure the frame244 and the window 114/116 to the wall 240.

Referring to FIG. 7, a diagram of an example implementation of a stickerlocated on an exterior side of the door 118 is shown. The sticker mayinclude a schematic (or wiring diagram) 260 of the electrical powerrouting, fuses (e.g., F1, F2, F3 and F4), and switches included in theisolated control panel 100. The schematic 260 generally allows theelectrical worker to see how the electrical power is routed from the topof the isolated control panel 100 (e.g., 575 volt 3-phase 60 Hertzline-side electrical power) to the electrical power transferred to theindustrial control panel 82 at the lower lefthand side of the schematic260.

Referring to FIG. 8, a perspective diagram of an example implementationof a portion of the interlock device 142 within the industrial controlpanel 82 is shown. The interlock device 142 may include a disk 270.While the door 118 of the isolated control panel 100 is open, the disk270 may be biased by a spring to reside in the path of a defeater lever96 of the main power disconnect handle 84. As shown, the disk 270 mayreside in a “de-energized” position that prevents the defeater lever 96from being moved downward. With the defeater lever 96 in an upwardposition, as shown, the main power disconnect handle 84 cannot be movedfrom the “off” position to the “on” position. The disk 270 may preventthe main electrical power from being turned on inside the industrialcontrol panel 82 and inside the isolated control panel 100 on the loadside past the main power disconnect switch 132.

Referring to FIG. 9, a perspective diagram of a portion of the interlockdevice 142 within the isolated control panel 100 is shown. The interlockdevice 142 may further include a rod 272 attached to the disk 270, and alatch 274 attached to the door 118. With the door 118 open, as shown,the rod 272 and disk 270 are biased toward the isolated control panel100 and may prevent the defeater lever 96 from being moved downward.

As the door 118 of the isolated control panel 100 is closed, a flange276 of the latch 274 may engage a free end of the rod 272. As the door118 continues to close, the flange 276 generally pushes the rod 272 anddisk 270 toward the industrial control panel 82 (e.g., to the left asillustrated) to an “intermediate” position. The movement caused by theflange 276 may be sufficient to cause the disk 270 to disengage thedefeater lever 96.

When door 118 reaches a fully closed position, the rod 272 may fall intoa slot 278 of the latch 274. With the rod 272 in the slot 278, the disk270 may be in an “energized” position and remain disengaged from thedefeater lever 96. The electrical work may now switch the main powerdisconnect handle 84 from the “off” position to the “on” position bycausing the defeater lever 96 to move downward with a tool. With themain power disconnect handle 84 in the “on” position, the cable actuator170 may close the main power disconnect switch causing the multi-phaseelectrical power to flow into the industrial control panel 82 from theisolated control panel 100.

The slot 278 may be shaped to interfere with the rod 272 while the door118 is in the closed position. Any attempt to open the door 118 with theinterlock device 142 in the “energized” position may be blocked by therod 272 striking against the latch 274. The interlock device 142generally prevents the door 118 from being opened if the main powerdisconnect handle 84 is in the “on” position or in the “off” position.

To return the interlock device 142 to the “de-energized” position, theelectrical worker generally opens the industrial control panel 82 andpulls the disk 270 away from the isolated control panel 100 to the“intermediate” position. While the disk 270 is in the “intermediate”position, the door 118 of the isolated control panel 100 may be openedby the operator. Once the latch 274 is clear of the rod 272, theoperator may release the disk 270, allowing the disk 270 to be biasedback into the “de-energized” position by the spring.

Referring to FIG. 10, a perspective diagram of an example implementationof a relief chamber 280 is shown. The relief chamber 280 may be attachedto a side (e.g., a top side) of the enclosure 101 over an opening in thewall of the enclosure 101. An end of the relief chamber 280 furthestfrom the enclosure 101 may include a screen area 282. The screen area282 is generally designed to allow hot gasses and flames from anarc-flash and/or arc-blast to pass through of the relief chamber 280 outinto the surrounding atmosphere in a predetermined direction. The screenarea 282 is generally oriented such that the hot gasses and flames aredirected away from an area in front of the door 118 where the electricalworker is commonly standing.

Referring to FIG. 11, a perspective diagram of the relief chamber 280from the enclosure 101 side is shown. The relief chamber 280 generallyincludes a door 284 and a latch 286. The door 284 may be hinged to swinginto an interior of the relief chamber 280. The door 284 may include ahandle. The latch 286 is generally configured to hold the door 284 in aclosed position.

In normal use, the latch 286 generally holds the door 284 in the closedposition. The closed door 284 may keep the interior of the isolatedcontrol panel 100 sealed from the outside environment. When anover-pressure situation from an arc-flash and/or arc-blast occurs, thepressure may push against the door 284. The latch 286 is generallyconfigured to release the door 284 when a specified pressure is reached.For example, the latch 286 may release when approximately 30 to 60pounds per square inch of pressure is exerted (e.g., from a 2,000 amperearc at 4 inches away). The pressure may push the door 284 open allowingthe hot gases and/or flames to pass into the relief chamber 280 andsubsequently out through the screen area 282.

Referring to FIG. 12, a block diagram of an example remote monitoringconfiguration is shown. All or some of the devices inside the isolatedcontrol panel 100 may be fitted with auxiliary signaling components (orsensors) that receive low-voltage electrical power. Each auxiliarysignaling component may provide one or more sensor signals to theprogrammable controller 226. The programmable controller 226 generallymonitors the status of each signal to determine a status of eachcorresponding device. The status of the devices may be pushed by theprogrammable controller 226 to a remote monitor 300 outside the isolatedcontrol panel 100. Bidirectional communication between the programmablecontroller 226 and the remote monitor 300 may be provided via a network(or communication channel) 302. In various embodiments, the network 302may be implemented as a wired network and/or a wireless network. In someimplementations, the network 302 may include, but is not limited to, anEthernet network, a Wi-Fi network or a cellular network. Other networksmay be implemented to meet the design criteria of a particularapplication.

The remote monitor 300 may be a standard information technology (IT)system so that any outside entity may monitor and track such things asmaintenance work (downtime), a circuit protector failure, an open dooralarm, power consumption, etc. The programmable controller 226 may alsobe used for local annunciation. For example, the programmable controller226 may control the horn/beacon 220 based on signals received from theauxiliary signaling components.

The isolated control panel 100 may include a fuse (or circuit breaker)304 on the power line 160 and a fuse (or circuit breaker) 306 on thepower line 162. The auxiliary signaling components generally comprise asensor (or switch) 310, a sensor (or switch) 312, a sensor (or switch)314, a sensor (or monitor) 316, a sensor (or monitor) 320, a sensor (ormonitor) 322, a sensor (or monitor) 324, a sensor (or monitor) 326 and asensor (or monitor) 330.

A signal (e.g., SWA) may be generated by the sensor 310 and received bythe programmable controller 226. The signal SWA may carry door 118open/closed information. A signal (e.g., SWB) may be generated by thesensor 312 and received by the programmable controller 226. The signalSWB may carry switch open/closed information for the main powerdisconnect switch 132. A signal (e.g., SWC) may be generated by thesensor 314 and received by the programmable controller 226. The signalSWC may carry switch open/closed information for the control powerdisconnect lever 112.

A signal (e.g., CT) may be generated by the sensor 316 and received bythe programmable controller 226. The signal CT generally conveys currentinformation for the electrical power entering the line-side powerdistribution block 130. A signal (e.g., FSA) may be generated by thesensor 320 and received by the programmable controller 226. The signalFSA may carry fuse status information for the fuse 304. A signal (e.g.,FSB) may be generated by the sensor 322 and received by the programmablecontroller 226. The signal FSB may carry fuse status information for themain power disconnect switch 132. A signal (e.g., FSC) may be generatedby the sensor 324 and received by the programmable controller 226. Thesignal FSC may carry fuse status information for the fuse 306. A signal(e.g., FSD) may be generated by the sensor 326 and received by theprogrammable controller 226. The signal FSD may carry fuse statusinformation for the control power disconnect lever 112. A signal (e.g.,ST) may be generated by the sensor 330 and received by the programmablecontroller 226. The signal ST may carry status information for the powerconverter 138.

The sensor 310 may implement a door switch configured to report anopen/closed condition of the door 118 in the signal SWA. The sensor 312may implement one or more switches configured to report an open/closedcondition of the switches of the main power disconnect switch 132 in thesignal SWB. The sensor 314 may implement a switch configured to reportan open/closed condition of the control power disconnect lever 112 inthe signal SWC. Other switch sensors may be implemented to meet thedesign criteria of a particular implementation.

The sensor 320 may implement a fuse status sensor configured to reportan open/closed condition of the fuse 304 in the signal FSA. The sensor322 may implement one or more fuse status sensors configured to reportan open/closed condition of the fuses of the main power disconnectswitch 132 via the signal FSB. The sensor 324 may implement a fusestatus sensor configured to report an open/closed condition of the fuse306 in the signal FSC. The sensor 326 may implement a fuse statussensors configured to report an open/closed condition of a fuse of thecontrol power disconnect lever 112 via the signal FSD.

The sensor 316 may implement multiple (e.g., three) current toroidsensors. Each of the current toroid sensor 316 may be configured toreport a current flow in a corresponding phase of the power line 150 inthe signal CT. The sensor 330 may implement a power converter statussensor. The power converter status sensor 330 is generally operationalto report a health of the power converter 138 in the signal ST. Othertypes of sensors may be implemented to meet the design criteria of aparticular application.

Referring to FIG. 13, a block diagram of another example implementationof a system 80 c is shown. The system 80 c may be a variation of thesystem 80 b with a modified industrial control panel 82 b and anextended enclosure 126. The extended enclosure 126 may be mounted below(as illustrated), above or to a side of the enclosure 101. The extendedenclosure 126 generally comprises a power line (or wires) 158 and aresistor bank 340. The receptacle 94 in the industrial control panel 82a (FIG. 4) may be duplicated as a receptacle 94 a and a receptacle 94 bin the industrial control panel 82 b.

The receptacle 94 a may be connected to the power line 156 through theapertures 140 a to receive multi-phase electrical power from theisolated control panel 100. The receptacle 94 b may be connected to theresistor bank 340 through the apertures 140 b and the power line 158.The resistor bank 340 generally comprises multiple (e.g., three)high-power resistors connected between the phases on the power line 158.

While and the industrial control panel 82 b is open, the rateddisconnect plug 92 may be manually disconnected from the receptacle 94 aand plugged into the receptacle 94 b. The receptacle 94 b generallyconnects the resistor bank 340 across the phases of the power line 90.The resistor bank 340 may discharge residual energy storage elements(e.g., capacitors or the like) present in the industrial control panel82 b making the interior of the industrial control panel 82 b safe.Before closing the industrial control panel 82 b, the disconnect plug 92may be manually disconnected from the receptacle 94 b and plugged intothe receptacle 94 a.

Referring to FIG. 14, a diagram of another system 80 d is shown. Thesystem 80 d may be a variation of the systems 80, 80 a, 80 b and/or 80c. The system (or apparatus) 80 d may include features of the systems80, 80 a, 80 b and/or 80 c. The system 80 d generally comprises anenclosure (or housing) 82 d and an enclosure (or housing) 100 a. Theenclosure 82 d may be a variation of the enclosures 82, 82 a, 82 band/or 82 c. The enclosure 82 d may implement a common industrialcontrol panel. The enclosure 100 a may be a variation of the enclosure100. The enclosure 100 a may implement an isolated control panel. Theisolated control panel 100 a may be mechanically attachable to anexternal side of the industrial control panel 82 d.

The industrial control panel 82 d may be operational to switch and/orroute high-voltage electrical power (e.g., 575 volts AC three-phasepower) from an input source to one or more external loads. In someembodiments, the industrial control panel 82 d may include the handle 84mounted on the front of the industrial control panel 82 d. In otherembodiments, the handle 84 may be omitted from the industrial controlpanel 82 d.

The isolated control panel 100 a generally comprises an enclosure (orhousing) 101 a and a door 118 a. The enclosure 101 a generally comprisesthe indicators 102, the test points 104, the indicators, 106, the testpoints 108, a handle (or switch) 109, the control power status light110, a handle (or switch) 111, the window 114, the optional window 116,the hinges 120 a-120 b, a lever (or handle) 122 and the one or morereceptacles 124

The enclosure 101 a may implement a rectangular-shaped box. Theenclosure 101 a may be configured to house various components andprovide mechanical protection against electrical shock hazards,arc-flash hazards and/or arc-blast hazards. The enclosure 101 a may befabricated of an electrically conductive material (e.g., steel) and iselectrically connected to the industrial control panel 82 d forgrounding purposes. In various embodiments, the enclosure 101 a may beseveral feet tall (e.g., 46 inches), by approximately a foot wide (e.g.,15 inches) and approximately a foot deep (e.g., 12 inches). Otherdimensions may be implemented to meet the design criteria of aparticular application.

The handle 109 may implement a main power disconnect handle having an“on” position and an “off” position. In some embodiments, the main powerdisconnect handle 109 may be a fused power disconnect handle. The mainpower disconnect handle 109 is generally operational to switchhigh-voltage electrical power (e.g., 575 volts AC three-phase power)from an input source to the industrial control panel 82 d. While themain power disconnect handle 109 is in the “on” position, the electricalpower may be transferred from a power line to inside the industrialcontrol panel 82 d. While the main power disconnect handle 109 is in the“off” position, the high-voltage electrical power may be isolated fromthe industrial control panel 82 d.

The handle 111 may implement a control power disconnect handle having an“on” position and an “off” position. The control power disconnect handle111 is generally operational to switch the high-voltage electrical power(e.g., 575 or 480 volts AC three-phase power) from the input source to apower converter that generates one or more lower voltages (e.g., 120volts AC single-phase power). While the control power disconnect handle111 is in the “on” position, the electrical power may be transferredfrom the power line to the power converter. While the control powerdisconnect handle 111 is in the “off” position, the high-voltageelectrical power may be isolated from the power converter.

The main power disconnect handle 109 and the control power disconnecthandle 111 may be mounted on a same side of the enclosure 101 a as thedoor 118 a. The handles 109 and 111 are usually mounted on a side of theenclosure 101 a (e.g., the right side) opposite the industrial controlpanel 82 d. To accommodate the handles 109 and 111, the hinges 120 a and120 b may be mounted inside the isolated control panel 100 a on the side(e.g., left) closest to the industrial control panel 80 d such that thedoor 118 a swings open (e.g., to the left) away from the handles 109 and111.

Referring to FIG. 15, a block diagram of an example implementation ofthe system 80 d is shown in accordance with an embodiment of theinvention. The industrial control panel 82 d generally includes thebranch circuit protector 86 (or a terminal connector or a distributionblock), the low-voltage wire 88, the power line 90, a control wire 404,a switch 406, a wire 408 and an electrical actuator 410. The isolatedcontrol panel 100 a generally includes the line-side voltage indicators102, the line-side test station 104, the load-side voltage indicators106, the load-side test station 108, the control power status light 110,the front window 114, the optional side window 116, the main powerdisconnect switch 132, the power converter 138, the apertures 140 a and140 b, the power line 150, the power line 152, the power line 154 andthe power line 156. The isolated control panel 100 a may also comprise ablock (or circuit) 112 a, a block (or circuit) 130 a, a block (orcircuit) 134 a, an interlock device (or mechanism) 136 a, an interlockdevice (or mechanism) 142 a, a power line (or wire) 160 a, a power line(or wire) 162 a, a power line (or wire) 164 a, a power line (or wire)165 a, a power line (or wire) 166 a, a power line (or wire) 168 a, anactuator (or rod or cable) 170 a, an actuator (or rod or cable) 170 b, apower line (or wire) 360, a block (or circuit) 362, a power line (orwire) 364, a block (or circuit) 366, a power line (or wire) 370, a block(or circuit) 372, a power line (or wire) 376, a block (or circuit) 378,a power line (or wire) 380, a power line (or wire) 400 and a block (orcircuit) 402.

The circuit 112 a may implement a control power disconnect switch. Thecontrol disconnect switch 112 a is generally operational to alternatelyconnect and disconnect the multi-phase electrical power received fromthe line-side power distribution block 130 a to the power converter 138.The control power disconnect switch 112 a may be controlled by theactuator 170 b.

The circuit 130 a may implement a line-side power distribution block.The line-side power distribution block 130 a is generally operational todistribute multiple-phase (e.g., three-phase) line-side electrical powerfrom the multi-phase power line 150 to the main power disconnect switch132. The electrical power may be transferred from the line-side powerdistribution block 130 a to the main power disconnect switch 132 via themulti-phase power line 152. In various embodiments, the line-side powerdistribution block 130 a may also distribute three-phase electricalpower to the circuit 112 a via the power line 168 a and three-phasepower to the circuit 362 via the power line 360. The current availableon the power lines 150, 152, 168 a and 360 may be a hazardous availablefault current.

The main power disconnect switch 132 is generally operational toalternately connect and disconnect the multi-phase electrical powerreceived from the line-side power distribution block 130 a to thecircuit 134 a via the power line 154. The main power disconnect switch132 may be controlled by the actuator 170 a.

The circuit 134 a may implement a load-side power distribution block.The load-side power distribution block 134 a is generally operational todistribute multiple-phase (e.g., three-phase) load-side electrical powerreceived from the main power disconnect switch 132 to the industrialcontrol panel 82 d via the multi-phase power line 156. The electricalpower from the output side of the load-side power distribution block 134a may be connected to the branch circuit protector 86, located in theindustrial control panel 82 d. The power line 156 may pass through oneor more apertures 140 a-140 b (e.g., 140 a) in the walls of the isolatedcontrol panel 100 a and continue in the industrial control panel 82 d asthe power line 90. The power line 90 is generally connected to thebranch circuit protector 86. The multi-phase electrical power receivedby the load-side power distribution block 134 a may also be transferredto the block 366 via the power line 364. Electrical power may also betransferred to the circuit 402 via the power wire 400.

The interlock device 136 a is generally operational to keep the door 118a in the closed position while the control power disconnect handle 111is in the “on” position. While the control power disconnect handle 111is in the “off” position, the interlock device 136 a may allow the door118 a to be open, if the interlock device 142 a permits. The interlockdevice 136 a may be defeatable with a standard tool. The interlockdevice 136 a may also prevent the control power disconnect handle 111from moving from the “off” position to the “on” position when the door118 a of the isolated control panel 100 a is open. The locking featureof the interlock device 136 a may also be manually defeatable.

The power converter 138 may receive electrical power from the line-sidepower distribution block 130 a through the control disconnect switch 112a. While the control disconnect switch 112 a is in the “on” position,electrical power may be supplied from the line-side power distributionblock 130 a, through power line 168 a, through the control disconnectswitch 112 a, and through the power line 166 a to the power converter138. While the control disconnect switch 112 a is in the “off” position,no electrical power is provided to the power converter 138. Thelow-voltage power may be presented by the power converter 138 on thepower line 370 while electrical power is received on the power line 166a.

The interlock device 142 a is generally operational to keep the door 118a in the closed position while the main power disconnect handle 109 isin the “on” position. While the main power disconnect handle 109 is inthe “off” position, the interlock device 142 a may allow the door 118 ato be open, if the interlock device 136 a permits. The interlock device142 a may be defeatable with a standard tool. The interlock device 142 amay also prevent the main power disconnect handle 109 from moving fromthe “off” position to the “on” position when the door 118 a of theisolated control panel 100 a is open. The locking feature of theinterlock device 142 a may also be manually defeatable.

The circuit 362 may implement a terminal with optional circuit breakersand/or fuses. The terminal 362 is generally operational to distributeelectrical power received from the line-side power distribution block130 a via the power line 360 to the line-side voltage indicators 102 andthe line-side test station 104 via the power line 160 a.

The circuit 366 may implement a terminal with optional circuit breakersand/or fuses. The terminal 366 is generally operational to distributeelectrical power received from the load-side power distribution block134 a via the power line 364 to the load-side voltage indicators 106 andthe load-side test station 108 via the power line 162 a.

The circuit 372 may implement a power distribution block. The powerdistribution block 372 may be operational to distribute electrical powerto the receptacles 124 via the power line 374 and to the circuit 378 viathe power line 376. The power distribution block 372 may also distributeelectrical power in the power line 380 through one of the apertures 140a-140 b (e.g., 140 b). Once inside the industrial control panel 82 d,the power line 380 may continue as a power line 89.

The circuit 378 may implement an AC-to-DC power converter. The powerconverter 378 may be operational to convert the 120 volt AC electricalpower received from the distribution block 372 to low-voltage electricalpower (e.g., 24 volt DC power). The low-voltage DC power may bepresented on the power line 165 a, through one of the apertures 140a-140 b (e.g., 140 b) to the interior of the industrial control panel 82d. The power line 165 a may continue as or be connected to thelow-voltage wire 88 inside the aperture 140 b. The power line 164 a maytransfer the low-voltage power to the control power status light 110.

The circuit 402 may implement a low energy power converter. The powerconverter 402 is generally operational to convert the high-voltageelectrical power received from the load-side power distribution block134 a to a low energy AC or DC power. The low energy power may bepresented through one of the apertures 140 a-140 b (e.g., 140 a) on thepower line 404 to the circuit 406.

The circuit 406 may implement a switch. In various embodiments, theswitch 406 may be a tool-operated rotary switch. The switch 406 isgenerally operational to alternately pass or block the low energy powerreceived from the power converter 402 from reaching the circuit 410 viathe power line 408. In some embodiments, the switch 406 may be mountedto a door of the industrial control panel 82 d. In other embodiments,the switch 406 may be mounted to the door 118 a of the isolated controlpanel 100 a. In such designs, the power line 404 may be internal to theisolated control panel 100 a and the power line 408 may route throughthe aperture 140 b to the circuit 410.

The circuit 410 may implement an interlock device. The interlock device410 may have shot pin that extends to a locked position while the lowenergy power is received from the switch 406. The shot pin may retractto an unlocked position when no low energy power is received from theswitch 406.

The shot pin in the locked position may interfere with a catch mechanismon the door of the industrial control panel 82 d thereby preventing thedoor from being opened. The shot pin in the unlocked position may clearthe catch mechanism thus allowing the door to be opened. When the mainpower disconnect handle 109 is in the “off” position, power to theinterlock device 410 may be removed (e.g., the load-side powerdistribution block 134 a is de-energized) allowing the door to beopened. The interlock device 410 may also be defeated by setting theswitch 406 to the “off” position thus allowing the door to be opened.

The functions and structures illustrated in the diagrams of FIGS. 1 to15 may be designed, modeled, emulated, and/or simulated using one ormore of a conventional general purpose processor, digital computer,microprocessor, microcontroller, distributed computer resources and/orsimilar computational machines, programmed according to the teachings ofthe present specification, as will be apparent to those skilled in therelevant art(s). Appropriate software, firmware, coding, routines,instructions, opcodes, microcode, and/or program modules may readily beprepared by skilled programmers based on the teachings of the presentdisclosure, as will also be apparent to those skilled in the relevantart(s). The software is generally embodied in a medium or several media,for example non-transitory storage media, and may be executed by one ormore of the processors sequentially or in parallel.

The terms “may” and “generally” when used herein in conjunction with“is(are)” and verbs are meant to communicate the intention that thedescription is exemplary and believed to be broad enough to encompassboth the specific examples presented in the disclosure as well asalternative examples that could be derived based on the disclosure. Theterms “may” and “generally” as used herein should not be construed tonecessarily imply the desirability or possibility of omitting acorresponding element.

While the invention has been particularly shown and described withreference to embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made withoutdeparting from the scope of the invention.

The invention claimed is:
 1. An apparatus comprising: an enclosure comprising a door and one or more apertures, wherein said enclosure is mechanically attachable to an external side of an industrial control panel with said apertures aligned to one or more openings in a wall of said industrial control panel; a power switch mounted inside said enclosure and configured to switch electrical power from a line-side power line to a load-side power line, wherein said load-side power line is configured to transfer said electrical power through at least one of said apertures; one or more power converters configured to generate a low-voltage electrical power from said electrical power; and a wire configured to transfer said low-voltage electrical power through at least one of said apertures.
 2. The apparatus according to claim 1, further comprising an additional power switch mounted inside said enclosure and configured to switch said electric power from said line-side power line to said power converters.
 3. The apparatus according to claim 2, further comprising a power disconnect handle mounted on said enclosure and configured to control said power switch.
 4. The apparatus according to claim 3, further comprising an additional power disconnect handle mounted on said enclosure and configured to control said additional power switch.
 5. The apparatus according to claim 4, further comprising a plurality of interlock devices configured to prevent said door from opening while at least one of said power disconnect handle and said additional power disconnect handle is at an on position.
 6. The apparatus according to claim 5, wherein said interlock devices are further configured to prevent each of said power disconnect handles and said additional power disconnect handles from moving from an off position to said on position while said door is open.
 7. The apparatus according to claim 2, wherein (i) said power converters are further configured to generate a single-phase electrical power from said electrical power and (ii) said single-phase electrical power is transferred through at least one of said apertures.
 8. The apparatus according to claim 7, wherein said single-phase electrical power is switchable by said additional power switch.
 9. The apparatus according to claim 2, wherein said power converters comprises a transformer configured to generate a single-phase electrical power from said electrical power switched by said additional power switch.
 10. The apparatus according to claim 9, wherein said power converters further comprises an AC-to-DC converter configured to generate said low-voltage electrical power from said single-phase electrical power.
 11. The apparatus according to claim 1, wherein said electrical power on said line-side power line has a plurality of phases.
 12. The apparatus according to claim 1, further comprising a plurality of test points (i) mounted on said door, (ii) accessible from outside said enclosure and (iii) configured to present at least one of (a) a phase-to-phase voltage and (b) a phase-to-ground voltage from each phase of said electrical power from said load-side power line.
 13. The apparatus according to claim 1, further comprising at least one of (i) a horn and (ii) a beacon configured to trigger while said door is open and said electrical power is present on said line-side power line.
 14. The apparatus according to claim 1, further comprising: a window mounted inside said enclosure; and a frame attached to said enclosure to secure said window against said enclosure.
 15. The apparatus according to claim 1, further comprising a programmable controller (i) mounted inside said enclosure, (ii) powered by said low-voltage electrical power and (iii) configured to report a plurality of sensor signals to a remote monitor external to said enclosure.
 16. The apparatus according to claim 1, further comprising a resistor bank configured to discharge energy stored in said industrial control panel.
 17. The apparatus according to claim 1, wherein said enclosure further comprises a relief chamber configured to direct at least one of (i) an arc-flash and (ii) an arc-blast out of said enclosure in a predetermined direction.
 18. A method for risk reduction of electrical hazards, comprising the steps of: switching electrical power with a power switch from a line-side power line to a load-side power line inside an enclosure, wherein (i) said enclosure is mechanically attachable to an external side of an industrial control panel with one or more apertures of said enclosure aligned to one or more openings in a wall of said industrial control panel and (ii) said load-side power line is configured to transfer said electrical power from inside said enclosure through at least one of said apertures; generating a low-voltage electrical power from said electrical power with one or more power converters; and transferring said low-voltage electrical power from inside said enclosure through at least one of said apertures.
 19. The method according to claim 18, further comprising the step of: switching said electrical power with an additional power switch from said line-side of said power switch to said power converters. 